Differences in road-crossing decisions between healthy older adults and patients with Alzheimer's disease.

INTRODUCTION: This study investigated the differences in road-crossing behavior among healthy older adults and patients with Alzheimer's disease (AD).

METHOD: Twelve pedestrians with mild AD and 24 age-, gender-, and education-matched controls were examined with a battery of cognitive, visual, and motor tests. Using a simulated two-lane, one-way road-crossing situation, we determined the remaining time and safety margin for each participant in traffic situations involving different vehicle speeds (40 km/h vs. 60 km/h vs. 80 km/h), time gaps (5 s vs. 7 s vs. 9 s), and time of day (dusk vs. midday).

RESULTS: We found that patients with AD were more vulnerable to traffic crash while crossing the road than healthy older adults (Odds Ratio = 2.50, P < 0.05). Compared with healthy older adults, patients with AD were more severely affected by daylight conditions, faster vehicle speed, and shorter time gap. Participants in both groups had a significantly higher risk of unsafe crossing behavior if they had lower scores on the Mini-Mental State Examination (MMSE), Complex Figure Test - recall (CFT-Recall), Trail Making Test (TMT) B-A, Useful Field of View (UFOV) - total, and Visual Form Discrimination (VFD). We also found that when given a long enough time gap (9 s), patients with AD and healthy older adults used similar safe road-crossing behaviors, independent of other factors.

PRACTICAL APPLICATIONS: These results provide important suggestions for road design for patients with AD and healthy older adults during road-crossing.